1. Field of the Invention
This invention relates generally to the field of medical equipment for respiratory therapy and more specifically to the user interface for a ventilator used for monitoring and controlling the breathing of a patient.
2. Description of the Related Art
Modern patient ventilators are designed to ventilate a patient's lungs with breathing gas, and to thereby assist a patient when the patient's ability to breathe on his own is somehow impaired. As research has continued in the field of respiration therapy, a wide range of ventilation strategies have been developed. For example, pressure assisted ventilation is a strategy often available in patient ventilators and includes the supply of pressure assistance when the patient has already begun an inspiratory effort. With such a strategy, it is desirable to immediately increase the pressure after a breath is initiated in order to reach a target airway pressure for the pressure assistance. This rise in pressure in the patient airway which supplies breathing gas to the patient's lungs allows the lungs to be filled with less work of breathing by the patient. Conventional pressure assisted ventilator systems typically implement a gas flow control strategy of stabilizing pressure support after a target pressure is reached to limit patient airway pressure. Such a strategy also can include programmed reductions in the patient airway pressure after set periods of the respiratory cycle in order to prepare for initiation of the next patient breath.
As patient ventilator systems and their various components, including sensors and control systems, have become more sophisticated, and more understanding is gained about the physiology of breathing and the infirmities and damage which form the requirements for respiratory therapy, the number of variables to be controlled and the timing and interrelationships between the parameters have begun to confront the caregiver with a daunting number of alternative therapeutic alternatives and ventilator settings. Also, in such a complex environment, the interface between the ventilator and the caregiver has often not been adaptable to the capabilities of the operator, thus running the chance of either limiting the choices available to a sophisticated user or allowing a relatively less sophisticated user to chose poorly from the alternatives presented. Thus, it would be beneficial if a ventilator interface guided the user through the setup or therapy modification process, illustrating the relationship between changes, preventing incorrect or dangerous settings and sounding alarms or other audible indications of invalid settings when something is about to be done that exceeds limits, but also allowing the advanced and sophisticated user to gain access to the full range of ventilator capabilities through an interface which both presents the various parameters and allows the visualization of their relationships.
Clinical treatment of a ventilated patient often requires that the breathing characteristics of the patient be monitored to detect changes in the breathing patterns of the patient. Many modern ventilators allow the visualization of patient breathing patterns and ventilator function and the caregiver adjusts the settings of the ventilator to fine tune the respiratory strategy being performed to assist the patient's breathing. However, these systems have been, up until now, relatively difficult to use by the unsophisticated user unless a limited number of options are selected. For example, in one prior art system, only a single respiratory parameter may be altered at a time. Moreover, the various respiratory parameters must often be entered into the ventilator controller in a prescribed order, or, where no order is prescribed, certain orders of entry should be avoided, otherwise the intermediate state of the machine before entry of the remaining parameters may not be appropriate for the patient. This inflexible approach to ventilator setup requires additional time and training if the user is to quickly and efficiently use the ventilator in a critical care environment.
Previous systems have also been deficient in that it is often difficult to determine the underlying fault that has caused alarms to be sounded, and what controls or settings should be adjusted to cure the problem causing the alarm. For example, prior alarm systems have consisted of nothing more than a blinking display or light with an alarm to alert the user that a problem existed. Similarly, many prior art systems provided only limited assistance to a user or technician in setting the parameters to be used during treatment. For example, if a technician attempted to enter a setting that was inappropriate for the patient because of body size or for some other reason, the only alarm provided may have been an auditory indication that the value was not permitted, but no useful information was provided to assist the technician in entering an appropriate setting.
One problem consistently presented by prior art ventilator control systems has been that the user interface has offered relatively little to guide and inform the user during the setup and use of the ventilator. Prior systems typically utilized a single visual display of the operating parameters of the ventilator and sensed patient parameters. Alternatively, prior systems may have numerous fixed numeric displays, certain of which may not be applicable during all ventilation therapies. Even when more than one display has been provided, users typically received limited feedback, if any, from the control system indicating the effect that changing one particular setting had on the overall respiratory strategy. If a parameter was to be adjusted, the display would change to display that particular parameter upon actuation of the appropriate controls, and allow entry of a value for that parameter. However, the user was provided with no visual cue as to how the change in the parameter value would effect the overall ventilation strategy, and thus had no assistance in determining whether the value entered for the parameter was appropriate for the patient.
What has been needed and heretofore unavailable in patient ventilators is a user friendly graphic interface that provides for simultaneous monitoring and adjustment of the various parameters comprising a respiratory strategy. Such an interface would also preferably guide sophisticated users in implementing ventilation therapies, provide guidance on the relationships between parameters as they are adjusted, allow rapid return to safe operation in the event that an undesirable strategy was inadvertently entered, provide alarms that are easily understood and corrected and present all of the relevant information in an easily understood and graphic interface. The present invention fulfills these and other needs.